Abstract: Mutagenesis and liposomal proton flux assays show that replacing the key residue (Asp-44) in the lipid-facing binding pocket with Ala has a dramatic effect on drug sensitivity, but that the channel remains fully drug sensitive when replacing Ser-31 with Ala.
Abstract: The solution structure of the S31N drug-resistant mutant of M2, a mutant of the highly pathogenic avian influenza subtype H5N1, shows that replacing Ser-31 with Asn has little effect on the structure of the channel pore, but dramatically reduces drug binding to the allosteric site.
Single mutation at the amino acid position 627 of PB2 that leads to increased virulence of an H5N1 avian influenza virus during adaptation in mice can be compensated by multiple mutations at other sites of PB2.
Abstract: Interestingly, one reverse mutation (K627E) took place at the amino acid position 627 of PB2 during passages of MA5 to MA15, indicating that a lysine at position 627 of PB2 is not absolutely needed for virulence and adaptation in mice by H5N1 virus.
Abstract: Taken together, the results suggest that mutations at multiple sites of PB2 contributed to the virulence and adaptation in mice, and the E627K mutation of PB2 is not an indispensable determinant in PB2 for mammalian adaptation by H5N1 avian influenza virus.
The origin and global emergence of adamantane resistant A/H3N2 influenza viruses.
Abstract: Adamantane resistance is associated with a single amino acid change (S31N) in the M2 protein, which was shown to rapidly disseminate globally in 2005 in association with a genome reassortment event.
Abstract: However, the exact origin of influenza A/H3N2 viruses carrying the S31N mutation has not been characterized, particularly in South-East Asia.
Abstract: We find that although the S31N mutation was independently introduced at least 11 times, the vast majority of resistant viruses now circulating globally descend from a single introduction that was first detected in the summer of 2003 in Hong Kong.
Me
Method: Independent introductions of the S31N replacement were inferred from clade positions on the M1/2 phylogeny and the location and dates of sampling.
Free energy simulations reveal a double mutant avian H5N1 virus hemagglutinin with altered receptor binding specificity.
PMID: 19399777
2009
Journal of computational chemistry
Abstract: Moreover, we predict that one double mutation (V135S and A138S) in HA significantly enhances alpha-2,6-linked receptor recognition by the H5 subtype.
Adaptive mutations resulting in enhanced polymerase activity contribute to high virulence of influenza A virus in mice.
Abstract: An isoleucine-to-leucine change at position 550 in PA further contributed to increased polymerase activity and high virulence, whereas all other mutations in PB1, PB2, and PA were irrelevant.
Abstract: In contrast, the virulent virus selected in the second adaptation experiment had a lysine-to-arginine change at position 208 in PB1 and a glutamate-to-glycine change at position 349 in PA.
Abstract: Mutational analyses demonstrated that an isoleucine-to-valine change at position 504 in PB2 was the most critical and strongly enhanced the activity of the reconstituted polymerase complex.|
Avian Influenza virus glycoproteins restrict virus replication and spread through human airway epithelium at temperatures of the proximal airways.
Abstract: Two of these viruses, A/Victoria/3/75 with L226Q and S228G mutations in hemagglutinin (HA) and neuraminidase (NA) from A/Chick/Italy/1347/99 and A/PR/8/34 containing the H7 and N1 from A/Chick/Italy/1347/99, exhibited temperature restriction approaching that of wholly avian influenza viruses.
Method: Mutant viruses were generated in either the A/Victoria/3/75 (H3N2) or A/PR/8/34 (H1N1) genetic background as follows: 1) Vic 627PB2; A/Victoria/3/75 containing a lysine to glutamic acid amino acid substitution at position 627; 2) Vic-226-228HA; A/Victoria/3/75 containing two amino acid substitutions in the HA gene (L226Q, S228G) that co
Identification of a Permissive Secondary Mutation That Restores the Enzymatic Activity of Oseltamivir Resistance Mutation H275Y.
Abstract: H275Y isolates were more likely than H275 isolates to have the mutations A209T and R224G in NS1 (chi(2)=284.9, df=2, p<0.0001).
Abstract: BACKGROUND: The H275Y mutation (H274Y in N2 numbering) in the neuraminidase (NA) gene (segment 6) of the influenza virus A (H1N1) genome is linked to oseltamivir resistance.
Abstract: CONCLUSIONS: During the 2007-2008 influenza season in Toronto, Ontario, Canada, 17% of influenza virus A (H1N1) isolates carried the H275Y mutation associated with oseltamivir resistance.
Abstract: OBJECTIVES: To determine the percentage of influenza virus A (H1N1) isolates that carry the H275Y mut
Influenza A virus NS1 targets the ubiquitin ligase TRIM25 to evade recognition by the host viral RNA sensor RIG-I.
Abstract: Furthermore, a recombinant influenza A virus expressing an E96A/E97A NS1 mutant is defective in blocking TRIM25-mediated antiviral IFN response and loses virulence in mice.
Result: Among the three viral IFN antagonist proteins tested, influenza A virus NS1 was unique in that it potently inhibited the RIG-I 2CARD ubiquitination; whereas the other IFN antagonists Ebola virus VP35 and vaccinia virus E3L showed no effect under the same conditions.
Result: As compared to titers achieved with WT virus, the E96A/E97A virus exhibited an approximately 1.5 log reduction in titer at 72 hours post-infection.
Result: At 24 hours post-infection with 100 pfu per egg, the titers obtained for the E96A/
Functional significance of the hemadsorption activity of influenza virus neuraminidase and its alteration in pandemic viruses.
Abstract: Using this hemadsorption-positive NA, we generated three NA variants with substitutions S370L, N400S and W403R that have been found in the hemadsorption site of human H2N2 viruses.
Abstract: We found that the NA of a representative pandemic virus A/Singapore/1/57 (H2N2) lacks hemadsorption activity and that a single reversion to the avian-virus-like sequence (N367S) restores hemadsorption.
A complicated message: Identification of a novel PB1-related protein translated from influenza A virus segment 2 mRNA.
Abstract: Removal of the PB1-F2 AUG upregulated N40 synthesis, while truncating PB1-F2 after codon 8 (with a concomitant M40I change in PB1) abolished N40 expression.
IV mutation literature information.
PMID: 
2009
Proc Natl Acad Sci U S A
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